Hello, I have another newbie question. This time about transistors (a basic 2n2222). In the image below you can see the result of a simple curcuit using a toggling jk flipflop where the two output lines are each driving a 2n2222 transistor. I'm experimenting a bit to get better fanout as these clocks is driving 8-10 different ICs (7400 series).
What I don't understand is the 4ms curve when the transistor turns off. Note - I'm using the NPNs where the load is on the emitter side - not the collector side. And that's my question. When used on the collector side I get fairly flat pulses - but this looks like a capacitor is in play and there's noe attached to the flip-flop. The input signal (the yellow one) is flat, and that's where the only capacitor is found.
5v
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2n2222 -- in signal from flip-flop
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(load - in this case just an LED with a 330ohm resistor)
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gnd
Sorry, crude drawing. I wanted to measure 0->5v so I thought putting the load on the emitter side would allow me to plot that out, but this is what I get. I understand that there is some resistance in the transistor - but obviously it looks like there's some kind of inductance too? This also seems to be within tollerances on the switching characteristics on the basic 2n2222 (25ns raise time) - I'm using a whopping 2.0 ms way above that. And as I stated if it is the transistor I would expect to see the same curve on the collector side? Since I don't I doubt I need to keep looking at the transistor, but at something else.
Basic question: What's causing this? Outside of putting the load "on the right side" is there anything that can be done to change this?